Circuit Diagram

Click to enlarge.

Four piezos each have a 1M ohm resistor across them, with the red wires each going to a different analog input (labeled D6, D9, D10, and D12).
This guide was first published on Jun 18, 2014. It was last updated on Jun 18, 2014. This page (Circuit Diagram) was last updated on Sep 16, 2019.